The present invention relates to a time measuring circuit for meters of the pulse reflection type such as an ultrasonic axial force meter, an ultrasonic thickness meter or the like.
For accurate measurement of a distance by using light, an axial force of a bolt or a thickness of an object by using ultrasonic waves, it is required to measure the distance, axial force or thickness with a resolution or resolving power of approximately 1 nS. To effect such accurate measurement, an expensive high speed counter has been utilized heretofore, resulting in provision of a special and complicated circuits for the counter.